1. Field of the Disclosure
The invention relates to a syringe body/needle assembly that avoids the use of organic adhesives for bonding syringe body and needle.
2. Description of Related Art
For manufacturing syringes, e.g. for pharmaceutical applications, the actual syringe body is usually formed from a glass tube using multistage hot forming processes. The syringe body as formed is then inspected and subsequently cooled in a lehr.
Syringe systems that are delivered filled with the drug to be administered, often have the needle already integrated. To this end, the needle may be glued into the syringe nozzle (also known as syringe cone) after the syringe body has been formed. The syringe cone may have any, not necessarily convergent shape. Below, a syringe cone refers to any nozzles having cross section shapes whose function is to reduce the fluid-carrying cross section compared with the plunger's diameter.
The needle is first introduced to the intended position in the nozzle, and is then fixed using a liquid organic adhesive which is added at room temperature and is cured, for example under ultraviolet light. Thereafter, the so prepared syringe body/needle assembly is cleaned, the inner wall of the syringe body is siliconized, and a cap is placed on the needle and nozzle. Then, this syringe system assembly is sterilized.
Filling of the syringe is then accomplished in the pharmaceutical companies which also place the final stopper with the plunger, for example for injection of the drug, and make the individual packaging.
During the storage period of the prefilled syringe, the drug is continuously in contact with the organic adhesive which fixes the needle in the syringe nozzle. Due to this direct contact between drug and adhesive, components of the adhesive may unintentionally diffuse into the drug and interactions between the drug and components of the adhesive may result. These effects may even be amplified by insufficiently hardened adhesives.
Moreover, when bonding the needle, adhesive might be introduced into the needle. This is particularly problematic when for example a UV-curable adhesive is used. The adhesive introduced into the needle is shielded from the incident UV light by the metallic needle and therefore will not cure, or at least not sufficiently. Uncured adhesive components may then interact with the introduced drug.
Especially proteins, but also DNA and/or RNA complexes can be very sensitive to the slightest contamination. Such contamination may cause conformational changes which then may considerably reduce the effect of the drugs or even eliminate it completely. Since in the modern pharmaceutical industry, more and more of such sensitive drugs are developed, produced and applied, the reduction of possible sources of contamination is becoming increasingly important.
In addition, both the process of siliconizing and the sterilization processes usually involve elevated temperatures. Since these processes are carried out after the needle has been bonded in the syringe body, the variety of possible methods that may be used for these processes is limited by the temperature resistance of the adhesive. Commercially available adhesives today exhibit a maximum temperature resistance of up to 150° C. But in order to be able to provide 100% pyrogen-free packing materials, a baked-on siliconization above 300° C. is required. However, many commercially available UV-curable adhesives lose their strength at these temperatures.
Fixation of needles in pharmaceutical syringes by means of an organic adhesive is described, for example, in documents U.S. Pat. No. 3,194,784 and U.S. Pat. No. 3,390,678.
Besides the use of organic adhesives, however, other methods for fixing the needle in or on the syringe body are known. For example, patent document U.S. Pat. No. 3,364,002 describes a method wherein a needle holder is directly introduced into fused glass of a syringe and so a fused bond is produced. In this case, however, the needle holder is heated to very high temperatures which may lead to a damage of the metal, for example by corrosion.